Problem: Sunny earns $\$12$ per hour delivering cakes. She worked for $x$ hours this week. Unfortunately, she was charged $\$15$ for a late delivery on Tuesday. How much money did Sunny earn this week? Write your answer as an expression. $\$$
Explanation: Let's see what happens as the number of hours worked increases: Number of hours worked Total Earnings ${2}$ $12 \cdot {2}-15 = 9$ ${3}$ $12 \cdot {3} -15= 21$ ${4}$ $12 \cdot {4} -15= 33$ Number of hours worked Total Earnings ${x}$ $12 \cdot {x}-15 = 12x-15$ The answer: $12x-15$